Control device for vacuum cylinders



Jan. 4, 1949. H. E. RICKETSON .CJNTROL DEVICE FOR VACUUM CYLINDERS FildOct. 25. 1945 glnuanfo Howard E. Riclceson/ l'l'o: new

Patented Jan. 4, 1949 UNITED sTATEs PATENT orrlcE comun DEVICE Fonvacuum crLmnEns Howard E. mere-tseu, United siam Anny ApplicationOctober 25, 1945. Serial No. 624.633 s claims. (ci. 12T-ss) (Grantedundelnie et or Maren s, lass. u amended April 30, 1928; 870 0. G. 757)The invention described herein may be manufactured and used by or forthe Goverment for governmental purposes, without payment to me of anyroyalty thereon.

This invention relates to vacuum cylinders and more particularly tocontrol devices therefor. Such cylinders are utilized for -manypurposes: and either the piston or the cylinder itself may move underthe influence of the vacuum while 'the other element remains stationary.

Generally stated, it is old in the art to employ vacuum cylinders withcontrol devices for adjusting its speed of operation, but such devicesare usually designed to eiIect an adjustment which does not varythroughout the stroke of the movable element.

I have found that in numerous installations greatly improved results maybe obtained by arranging for the movable element to travel atprogressively slower speeds along the length of its stroke. Morespecifically, this will result in the cushioning of undesirable shockwithout appreciable retardation of the operating cycle.

In vacuum-controlled excavating machines of the shovel-and-crane type,for example, considerable dililculty is presented for the reason thatbecause of the necessity of having to exhaust the air from the line andfrom the vacuum cylinder before the clutch will engage there develops atime lag between the instant thatthe operator opens the control valveand thev moment the clutch actually engages: and during this time lag,the operator opens the control valve too wide. This excessive opening ofthe control valve causes the ultimate sharp egagement of the clutch witha resultant jerky and violent operation accompanied by injurious shockto the machine.

Certain expedients (such as the use of a restrictor at a suitable pointin the vacuum line) result in smoothing out the engagement of theclutch; but the use thereof slows down the operation of the vacuumcylinder and increases the time lag both on engagement and also on therelease of the clutch. This is objectionable from an operational pointof View.

It is among the objects of the present invention to provide a controldevice for vacuum cylinders which will result in an even action withoutincrease in time lag.

Another object is to so control the air input of a device of the classdescribed as to cause progressively decreasing speed in the operatingstroke to thereby prevent injury from suddenly imposed strains, and atthe same time, provide for a rapid output or exhaust on the returnmovement.

Another object is the provision of a vacuum cylinder wherein theadmission of air under atmospheric pressure is metered, together withmeans for eiecting the rapid exhaust referred to. 60.

With such construction and arrangement, the operator ot the machine (forexample, the shoveland-crane previously mentioned) may move the controlvalve wide open, but the clutch will engage smoothly and only as fast asthe metering eiiect will permit; while the rapid exhaust means enablesinstantaneous release.

Still another object is to provide a device of the class described whichis cheap and easy to manufacture and durable in service.

'I'he invention, then. comprises the features hereinafter fullydescribed. and as particularly pointed out in the claims..the followingdescription and the annexed drawingssetting forth inv detail certainillustrative embodiments of the invention, these being v'indicative ofbut4 several of numerous ways in which the principles of the inventionmay be employed.

In said drawings:

Figure I is a longitudinal view, mostly kin section, illustrating'theassociation of the operating instrumentaiities `of---the device. ofthe-invention wth the vacuum cylinder and the pistons disposed therein;

Figure 2 is a view similar to that of Fig.. 1, but discloses apermissive modification: and

Figure 3 is a sectional view on the line 3-3 of Fig. 2.

Referring more'particularlyto the drawings the numeral 2 designates avacuum lingel from a suitable source of low pressme, the said linebein'g connected, to a vacuum cylinder 3. In the manner well known inthe art. the vacuum cylinder 3 is provided with a connector 4 by whichthe said cylinder is connected to the element which it is intended tooperate, for example, the operating lever of a mechanical clutch (notshown). Within the vacuum cylinder 3 is a piston 5 to which there isconnected a piston rod 6, the latter projecting from the said cylinderas shown. This piston rod 6 may, if desired, be conveniently anchoredand thus rendered immobile.

The vacuum cylinder 3 and its interiorly disposed piston 5 are ci moreor less conventional design. However, the piston rod 6 is of modieddesign as will appear. This piston rod 6 is provided with a centralpassage 9 which is closed at its ends. The inner end ot the centralpassage 9 communicates with a right angularly extending port ill whichin turn communicates with the inside of the vacuum cylinder 3 at a pointimmediately adjacent the proximate face oi the piston 5. At appropriatepoints along its length, the piston rod E is provided with air inletports, as shown at l2, i3 and I4, the latter beingdispos'ed adjacent theouter end of the said piston rod.

'Both ends of the vacuum cylinder 3 are closed as shown at Ivand l1, andthe closure l1 from which the piston rod 6 projects is provided with acentrally disposed sleeve I8 which serves as a bearing. The outer end ofthis centrally disposed sleeve I8 projects from the closure I1 andcarries an annularly rotatable collar which is secured against rotationand/or longitudinal movement by a set screw 2|. As shown in Figure l theannular collar 20 closely embraces the piston rod 6 and is provided witha peripheral recess which is defined by a longitudinally extending wall22 and a fiat angular wall 23 which extends inwardly and converges uponthe longitudinally extending wall 22. Thus, the walls 22 and 23 of thecollar 2|) define a right-angled triangle, the apex of which liesinwardly of the outer end of the said collar.

Accordingly, to the foregoing construction and arrangement, theatmospheric air entering the vacuum cylinder 3 is metered through theair inlet ports I2, I3 and I4 in the piston rod 8. The hole i4 is alwaysexposed, but extent of exposure of the holes I2 and I3 is regulated bythe adjustment of the rotational position of the triangular recess inthe annular collar 2D. Thus, when all three holes (i. e. I2, -I3 and I4)are exposed, the vacuum inlet end of the vacuum cylinder 3 is drawntoward the piston rod 6 at a rate which is initially very rapid anddecreasingly slower as the exposure of the holes and I2 and I3 isforeclosed. This metering effect accomplishes the results referred tohereinbefore.A

In order to assure the quick return of the vacuum cylinder 3 to itsinitial position, the closure I7 which is on the atmospheric air" sideofthe piston 5, is provided with a quick-operating disk-type of exhaustvalve 25 which, upon being operated by the air pressure in theatmospheric air" pressure side of the piston, releases the air andvpermits the cylinder to .drop to its initial position under gravity,that is, by its own weight.

In Figure 2 of the drawings there is shown a modified form of meteringdevice; the same comprising a slot 26 which extends from the inner endof the piston rod B to a point adjacent the outer end thereof. This slot26 is a dove-tail contour, being defined by a fiat bottom 21, and a pairof outwardly convergent iiat side walls 28. Within the dovetail slot 26there is disposed a slidable wedge 30, the -bottom and side walls ofwhich conform to the size and shape of the corresponding portions of thesaid slot, as shown in-Figure 3 of the drawings.

outer surface inwardly toward the piston 5. A bushing 32 or othersuitable sealing means may be disposed within the sleeve I8 as shown.Whether using either the embodiment of Figure 1, or the permissivemodification of Figure 2, the intake of air at atmospheric pressure intothe vacuum cylinder 3 is metered to provide for rapidinitial movementfollowed by progressive decrease as the vacuum cylinder 3 moves towardthe piston 5.

Having thus described my invention, what-If claim as new and wish tosecure by Letters Patents is:

The wedge formation of the slldable wedge accrues from the tapering ofits 2. A vacuum cylinder assembly comprising a vacuum cylinder providedwith -a closure at both ends, a piston disposed within said cylinder,means for connecting one end of said cylinder with a source of vacuum, apiston rod extending through the closure at the other end of saidcylinder and connected to said piston, a check valve permitting a rapidexhaust flow from the cylinder to the atmosphere carried by thelast-named end of said cylinder, said piston rod having a centralpassage communicating with the adjacent side of said piston and spacedair inlet openings communicating with the atmosphere, and means forclosing at least one of said spaced air inlet openings during theoperating stroke of said vacu um cylinder.

3. A vacuum cylinder assemblyvcomprising a vacuum cylinder providedwitha closure at both ends, a piston disposed within said cylinder,means for connecting one end of said cylinder with a source of vacuum, apiston rod extending through the closure at the other end of saidcylinder and connected to said piston, a check valve permitting a rapidexhaust ilow from the cylinder to the atmosphere carried by thelast-named end of said cylinder, said piston rod having a centralpassage communicating with the adjacent side of said piston and spacedair inlet openings communicating with the atmosphere, means for closingat least one of said spaced air inlet openings during the operatingstroke of said` vacuum cylinder, said last-namedmeans comprising anadjustable sleeve on the exterior-of said cylinder, and means foradjustably positioning said sleeve to regulatethe extent of operation ofat least one of saidl spaced air inlet openings.

4. A vacuum cylinder assembly comprising a vacuum cylinde'nprovided witha closure at both ends, a piston disposed Within said cylinder, meansfor connecting one" end of said cylinder with a source of vacuum, apiston rod extending through the closure at the other end of saidcylinder and connected to said piston, a check valve permitting a rapidexhaust flow from the cylinder to the atmosphere carried by thelast-named end of said cylinder, said piston rod having a longitudinalslot, and a wedge disposed in said slot, said wedge being longitudinallyadjustable to vary the size of the opening between said slot and theadjacent cylinder closure at any given position in the operating strokeof said vacuum cylinder. H

5. A vacuum cylinder assembly comprising a stationary piston, a closedcylinderreciprocably mounted-on said pistone, a piston rodconnected tosaidv piston and extending `exteriorly of said cylinder, means forconnecting one end of said cylinder to a source of Vvacuum whereby oneside of saidpiston is in 'contact with said vacuum, a check valvemounted; on the other end of Asaid cylinder, said check valve permittinga rapid exhaust flow from the 'cylinder to the atmosphere, and a meansfor metering atmospheric air to the last mentioned end of said cylinderwhereby air may be applied to the other side of said piston.

, HOWARD E. RICKETSON.

. REFERENCES CITED l UNITED sTA'rEs PATENTS Number

